The present invention relates to a pharmaceutical composition for oral or injectable (parenteral) use containing 2-(4-isobutylphenyl) propionic acid and a basic amino acid, and more particularly, where the amino acid is arginine.
2-(4-isobutylphenyl) propionic acid, whose International Nonproprietary Name is ibuprofen, is a well-known anti-inflammatory drug having a molecular weight of 206.28 and the following chemical structure: 
(Merck Index 12th ed., n4925, page 839). Originally patented in the 1960""s, ibuprofen is now marketed generically, as well as under the tradenames of Motrin(copyright), Advil(copyright), and Nuprin(copyright) for the treatment of pain, inflammation, and fever.
Ibuprofen is readily available as the racemic mixture ((RS)-Ibuprofen) of the two enantiomers, (R)-Ibuprofen and (S)-Ibuprofen. Even though the (S) enantiomer is the biologically active form, most preparations contain the racemic mixture since the (R) enantiomer is converted to the active (S) form in-vivo. For simplicity, hereinafter the term xe2x80x9cibuprofenxe2x80x9d will be used to indicate any one of the (R) enantiomer, the (S) enantiomer, or the racemate.
Many amino acids, including arginine, are available as both the D and L forms. For simplicity, hereinafter the term xe2x80x9cargininexe2x80x9d will indicate the D or L form of arginine or a mixture of (D)-arginine and (L)-arginine. Arginine has a molecular weight of 174.20.
Although ibuprofen has many advantages over other analgesics such as aspirin and acetaminophen, it is very poorly soluble in water. Thus, certain dosage forms of ibuprofen, especially oral or injectable liquids, have been difficult to develop. Several U.S. patents have addressed this problem.
For example, U.S. Pat. No. 4,309,421 appears to describe water-soluble complexes of ibuprofen and phospholipids suitable for parenteral administration. U.S. Pat. Nos. 4,859,704 and 4,861,797 appear to describe the synthesis of alkali metal salts of ibuprofen for preparing a liquid ibuprofen formulation.
Other U.S. patents appear to address this problem by preparing an ibuprofen salt with a basic amino acid as the active pharmaceutical ingredient and then solubilizing the salt to produce a liquid dosage form.
For example, U.S. Pat. No. 5,200,558 appears to describe enhanced analgesic effects of S (+) ibuprofen as salts of L and D amino acids, including arginine, in various dosage forms, including as an injectable solution. U.S. Pat. No. 4,279,926 appears to describe the use of basic amino acid salts of propionic acids for relieving pain and treating inflammatory conditions. Similarly, U.S. Pat. No. 5,463,117 appears to describe the preparation of salts of ibuprofen with basic amino acids. Finally, U.S. Pat. No. 6,005,005 appears to describe a liquid composition for oral use containing ibuprofen and arginine.
However, the approaches described in the patents discussed above have, among others, the disadvantage of requiring the formation of a salt before solubilization, where the salt must be isolated and tested prior to producing the dosage form. Additionally, the ibuprofen formulations resulting from those processes have at least a 1:1 molar ratio of amino acid to ibuprofen. It is beneficial from both a cost and development point to not have to form a salt and isolate and test it prior to producing the dosage form. It is also beneficial in most cases to minimize the amount of non-active components, including salts, used in therapeutic products in order to minimize potential side effects. Furthermore, for injectable products it is beneficial to produce a liquid dosage form of ibuprofen having a pH similar to that of blood (pH 7.4). Finally, it is beneficial for an injectable and oral product to have similar pharmacokinetics to minimize the need for dosage adjustments.
The present invention utilizes arginine to solubilize ibuprofen during the manufacture of the pharmaceutical product instead of using a salt form of ibuprofen. Thus, an embodiment of the present invention is a pharmaceutical composition comprising an aqueous solution of arginine and ibuprofen, wherein the molar ratio of arginine to ibuprofen is less than 1:1. Another embodiment of the present invention is a method of making a pharmaceutical composition comprising an aqueous solution of arginine and ibuprofen, wherein the molar ratio of arginine to ibuprofen is less than 1:1. Still other embodiments of the present invention are directed to methods of treating pain, inflammation, fever, and/or other conditions alleviated by ibuprofen comprising administering a pharmaceutical composition comprising an aqueous solution of arginine and ibuprofen, wherein the molar ratio of arginine to ibuprofen is less than 1:1.